A power amplifying element includes a drain electrode, a gate electrode, and a source electrode. A high frequency amplifying device includes a plurality of power electrifying elements connected in parallel to obtain a high gain.
When a plurality of drain electrodes of this high frequency amplifying device is connected in one direction and a plurality of gate electrodes is connected in the other direction, an isolated source electrode is left when the number of power amplifying elements is four or more, and there is an issue of how to ground this isolated source electrode.
With a conventional high frequency amplifying device, in order to ground this isolated source electrode, a coupling part for grounding source electrodes at both ends of a plurality of power amplifying elements connected in parallel and this isolated source electrode are connected by plating wiring crossing a pair of a drain electrode and a gate electrode. This plating wiring is referred to as air plating wiring or air bridge.
However, if the air bridge is used, the distances from the isolated source electrode to via holes for grounding become long. When the distances from the source electrode to the via holes become long, there is an issue that an inductance occurs at a high frequency and a gain of the high frequency amplifying device decreases.
An amplifying device is demanded which further reduces the distances from the source electrode to the via holes, and reduces an influence of an inductance as much as possible.